Question 1

Which of the following is not a common type of receptor?

Accepted Answer

Adenylyl cyclase is an enzyme, not a receptor. It converts ATP to cyclic AMP in response to a signal.

Question 2

Which of the following statements about cell signaling in voles is false?

Accepted Answer

Oxytocin acts as a signal for mating behaviors, not premating behaviors in voles.

Question 3

Plasmodesmata and gap junctions

Accepted Answer

Both plasmodesmata and gap junctions are channels that allow small molecules and ions to pass rapidly between cells. Plasmodesmata are found in plants, while gap junctions are found in animal cells.

Question 4

Which of the following is not a consequence of a signal binding to a receptor?

Accepted Answer

Breakdown of the receptor to amino acids is not a consequence of a signal binding to a receptor. Instead, it is a consequence of receptor degradation or turnover, which can occur under certain conditions but not necessarily as a direct result of signal binding. The other choices (A, B, C, and E) are all potential consequences of signal binding, depending on the specific receptor and signaling pathway involved.

Question 5

Signals reach target cells in multicellular organisms via _______ and _______.

Accepted Answer

Signals in multicellular organisms typically reach target cells through circulation, where they are transported via the bloodstream, and diffusion, where they move across cell membranes or through interstitial spaces to reach their target cells.

Question 6

The signals that bind to receptors on nearby cells are known as

Accepted Answer

Paracrine signals are produced by one cell and bind to receptors on nearby cells, often regulating local cellular communication and behavior.

Answer: C 
 Autocrine signals are produced by a cell and bind to receptors on that same cell, often regulating its own function and behavior.

Option B and D are incorrect as parasitic signals and hormones are not signals that bind to receptors on nearby cells, but rather affect other organisms or distant parts of the body, respectively. Option E is not a commonly recognized term in this context.

Question 7

What is the correct order for the following events in the interaction of a cell with a signal? (1) Alteration of cell function; (2) signal binds to receptor; (3) signal released from source; (4) signal transduction.

Accepted Answer

The answer of What is the correct order for the...

Question 8

The first component of a signal transduction pathway is a(n)

Accepted Answer

The first component of a signal transduction pathway is the receptor, which receives signals from the environment or other cells. The receptor then triggers a series of events that activate downstream components, leading to a cellular response.

Question 9

The major difference between a cell that responds to a signal and one that does not is the presence of a

Accepted Answer

Cells that respond to a signal have receptors that specifically bind to the signal molecule, initiating a signaling cascade that ultimately leads to a cellular response. Cells that do not respond to the signal lack these receptors. Choices A, B, D, and E may be important components of the signaling pathway, but they do not specifically differentiate between responsive and non-responsive cells.

Question 10

Steroid hormones such as estrogen act on target cells by

Accepted Answer

Steroid hormones are able to pass through the cell membrane due to their lipid-soluble nature. Once inside the cell, they bind to specific receptors in the cytoplasm which then translocate into the nucleus and bind to specific DNA sequences. This results in the initiation of gene expression and the production of new proteins that affect cell function.

Question 11

Which of the following is not a second messenger?

Accepted Answer

Calcium ion, inositol triphosphate, cyclic AMP, and diacylglycerol are all considered second messengers because they are involved in signaling pathways that are activated by extracellular ligands binding to cell surface receptors. ATP, on the other hand, can act as a neurotransmitter or energy source within the cell, but it is not typically considered a second messenger.

Question 12

Cells receive which of the following signals?

Accepted Answer

Cells can receive various types of signals including light, sound, odorants, and hormones, depending on the type of cell and its function.

Question 13

Which of the following statements is false?

Accepted Answer

All the statements A, B, C, and D are true, so none of them is false.

Question 14

Which of the following is not true of a protein kinase cascade?

Accepted Answer

Protein kinase cascades do not typically end up at the mitochondrion. They usually end at the nucleus or cytoplasm where target proteins are phosphorylated, leading to changes in cellular behavior.

Question 15

A nonpolar molecule such as a steroid hormone usually binds to a

Accepted Answer

Nonpolar molecules such as steroid hormones are able to diffuse through the plasma membrane and bind to intracellular receptors in the cytoplasm or nucleus. Therefore, they typically bind to cytoplasmic receptors.

Question 16

Why do some signals ("first messengers") trigger "second messengers" to activate target cells?

Accepted Answer

The first messenger cannot cross the plasma membrane, therefore it needs to activate a second messenger within the cytoplasm to relay its signal to target cells inside the cell.

Question 17

The signals that bind to receptors of the same cell that made them are known as

Accepted Answer

Autocrine signals bind to receptors on the same cell that secretes them.

Question 18

Which of the following statements is true?

Accepted Answer

Light can be a signal that cells can respond to. A classic example is photosynthesis, in which plant cells use light as a signal to drive the process of converting carbon dioxide and water into glucose and oxygen.

Question 19

Most of the chemical signals coming to a cell deep inside a multicellular organism come from

Accepted Answer

Most of the chemical signals that a cell receives in a multicellular organism come from other nearby cells. These signals, which can be in the form of hormones, neurotransmitters, or growth factors, help to coordinate the activities of different cells and tissues within the organism. While the external environment and the nervous system can also play a role in cellular signaling, they are not typically the primary sources of signals for cells within the body. The lymphatic system is primarily involved in immunity and the maintenance of fluid balance, and is therefore not a major source of signaling molecules for most cells.

Question 20

To respond to a signal, a cell must have a(n) _______ molecule that can detect the signal.

Accepted Answer

A receptor molecule is essential for responding to a signal. Paracrine and autocrine molecules can act as signals, but they are not directly involved in the cell's response. "Responder" is not a term used in the context of cellular signaling.

Quiz 7: Cell Signaling and Communication